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  • autofluorography  (2)
  • Bone Gla protein  (1)
  • 2015-2019
  • 2010-2014
  • 1990-1994  (3)
  • 1945-1949
  • 1993  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Lack of change of cancellous bone volume with short-term use of the new immunosuppressant rapamycin in rats (1993)
    Springer
    Calcified tissue international 53 (1993), S. 45-52 
    Details
    ISSN: 1432-0827
    Keywords: Rapamycin ; Bone mineral metabolism ; Bone Gla protein ; Immunosuppressants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Immunosuppressants have adverse effects on bone mineral metabolism in animal and human studies, with corticosteroids producing low-turnover osteopenia, and cyclosporin-A (CsA) producing high-turnover osteopenia. Rapamycin (RAPA) is a new immunosuppressant reported to be at least 10 times more potent than CsA, and acts via a different pathway to CsA and the other new immunosuppressant FK506. This study investigated the effects of RAPA on bone mineral metabolism in the rat. Forty-two, 10-week-old, male Sprague Dawley rats were divided into three groups, and treated according to the following protocol: group A (control) received RAPA vehicle by daily gavage for 14 days (n = 12); group B (high dose RAPA) received RAPA 2.5 mg/kg/day by daily gavage for 14 days (n = 15); group C (low dose RAPA) received RAPA 1.25 mg/kg/day by daily gavage for 14 days (n = 15). Rats were weighed and bled on days 0, 7, and 14 for measurement of blood ionized calcium, bone Gla protein (BGP), parathyroid hormone (PTH), and 1,25(OH)2D. Tibial bone histomorphometry was determined on day 14 after double-calcein labeling. Weight gain was similar in the two groups treated with RAPA compared with control animals. High-dose RAPA (group B) transiently depressed serum BGP levels on day 7, with elevated blood ionized calcium levels on day 7, and lowered 1,25(OH)2D levels on day 14. Serum PTH levels were unchanged. Low dose RAPA (group C) did not affect calciotropic hormones. Histomorphometric analyses of tibial metaphyses revealed that parameters of bone formation and resorption were not significantly different in the groups treated with RAPA (group B and C) compared with control animals (group A). Trabecular bone volume (BV/TV) in group B (high-dose RAPA) (15.39 ± 1.01%) and C (low-dose RAPA) (15.38 ±0.57%) was not significantly altered compared with group A (control) (16.42 ± 0.86%). Short-term treatment with RAPA, unlike CsA, does not result in excess resorption and loss of bone volume. The depressed serum 1,25(OH)2D levels seen with high-dose RAPA therapy may adversely effect bone mineral metabolism in the long term.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01352014
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  • 2
    Electronic Resource
    Electronic Resource
    Uptake and metabolism of indole-3-butyric acid and indole-3-acetic acid by Petunia cell suspension culture (1993)
    Springer
    Plant growth regulation 13 (1993), S. 31-40 
    Details
    ISSN: 1573-5087
    Keywords: autofluorography ; IBA aspartic acid ; IBA glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake and metabolism of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) were studied in suspension cell cultures of Petunia hybrida. The initial uptake of 3H-IBA was much higher than that of 3H-IAA, and after 10 min of incubation with labeled IBA and IAA, 4.6 pM vs 0.35 (39% vs 12% of total applied radioactivity) respectively, were found in the cell extracts. The uptake of IBA reached a plateau of 6.0 pM (62%) after 2 h while that of IAA increased continuously up to 1.5 pM (46%) after 24 h. Following the addition of 40 µM of unlabeled auxin more IBA was taken in initially than IAA (39% vs 12%), but the level almost equalized after 24 h of incubation when IBA uptake reached 890 nM (55%) and IAA 840 nM (46%). IBA was metabolized very rapidly by Petunia cell suspension to new compounds. HPLC of the cell extracts demonstrated a new metabolite after only 2 min of incubation, and after 30 min 60% of the radioactivity was in the new metabolite vs 10% in the IBA. The new compound was resolved by autofluorography to two metabolites but after 24 h only one metabolite was present. The IBA metabolites were identified tentatively as IBA aspartic acid (IBAasp) and IBA glucose (IBAglu). In the medium IBA disappeared at a fast rate and after 24h most of the radioactivity was present in the new metabolite, probably IBAasp. IAA was also converted rapidly to two new metabolites and both were still present after 24 h. No attempt was made to identify the metabolites of IAA. IAA metabolism proceeded at a slower rate, and autofluorography showed that while free IBA disappeared after 0.5 h, free IAA was still present after 1 h of incubation. We postulate that Petunia cells conjugate IBA rapidly to IBAglu which in turn is converted to form IBAasp which probably acts as a ‘slow release’ hormone. Only intact cells were able to metabolize IBA and the reaction was affected by low temperature and anaerobic conditions. The fast rate of IBA uptake, the need for whole cells for the metabolism to proceed, and the fast change of IBA to a new metabolite in the medium, all suggest that both uptake and metabolism of IBA in Petunia cells occur on the cell surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00207589
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  • 3
    Electronic Resource
    Electronic Resource
    Indole-3-butyric acid in Arabidopsis thaliana (1993)
    Springer
    Plant growth regulation 13 (1993), S. 189-195 
    Details
    ISSN: 1573-5087
    Keywords: Arabidopsis thaliana ; autofluorography ; auxin conjugates ; IBA-glucose synthase ; indole-3-butyric acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Indole-3-butyric acid (IBA) was metabolized by seedlings of Arabidopsis thaliana cultivated in liquid medium under sterile conditions to two major metabolites. One metabolite was hydrolyzed by 1 N NaOH and β-glucosidase and was tentatively identified as IBA-glucose and the other was hydrolyzed by 7 N NaOH and amidase and was identified as an amide-linked conjugate. IBA-glucose synthase activity was found in a soluble enzyme fraction after incubation of 3H-IBA, IBA and UDP-glucose. The labelled reaction product had an Rf value comparable to IBA glucose and stained positive with Ehmann reagent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024261
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